Removed SeededModule for much clearer new() methods.

Also added some initial tests of the error conditions for Billow
and Pink noises, and fixed several small documentation errors.

Signed-off-by: Atheriel <atheriel@gmail.com>
Started implementing the geometric noise types.

This commit includes constant and cylindrical noise implementations.

Signed-off-by: Atheriel <atheriel@gmail.com>
Restructured the API using re-exports.

Signed-off-by: Atheriel <atheriel@gmail.com>